For a starting player you would want to hit both Arena and Fleet.
My suggestion:
EP, Vader, Tarkin, TFP, Thrawn
If you do not have good mods and your Vader is slower than others', use Thrawn lead.
I could hang in top 10, sometimes top 20 with this arena squad.
The past 2 weeks have been harder for me because everybody else is starting to zeta both Sion and EP.
I do not have any zetas in mine. I still expect to keep top 20 in the following weeks with Thrawn lead.
Saving my zetas for JTR and BB8.
Once you have a stable ranking in fleet, you could start gearing Sion and DN if you wish to invest in Nightmare since Traya is coming. I myself choose to use zetas on my Raiding squads.